A generic actuator of said type is known from DE-102 40 774 A1. Proceeding from the retracted, inner position of the engagement pin, an activation of the engagement pin is realized through energization of the coil, as a result of which a magnetic field is generated which opposes the field of the permanent holding magnet and displaces the latter. The displacement of the field results in a reduced holding force between the permanent holding magnet and the coil core, such that the magnetic field generated by the coil and the force of the spring acting on the engagement pin causes a deployment of the engagement pin, such that the latter engages into the groove of the sliding cam and, as desired, effects a displacement of the sliding cam.
The return movement of the engagement pin into its inner end position is initiated by the ejection ramp, the aim of which is to move the engagement pin away from the sliding cam counter to the force of the spring to such an extent, and with such an acceleration, that the engagement pin, when the coil is deenergized, is held fixed by the permanent holding magnet and the magnetic field thereof on the coil core.
A problem of this generic design is that, depending on the tolerances of the actuator radially with respect to the sliding cam, the movement and acceleration of the engagement pin by the ejection ramp is not sufficient to ensure that the engagement pin reaches the inner position and is stabilized counter to the force of the spring by the permanent holding magnet.
Furthermore, there is the problem that, in the case of sliding cam systems with three or more sliding cams, at least two engagement pins must be provided. Here, a small spacing of the engagement pins is demanded, said spacing being predefined by the spacing of the gas exchange valves, the spacing of the cylinders of the internal combustion engine and the number of sliding cams. As a result of the small spacing, the design of the actuator described in the prior art is no longer capable of moving and holding the engagement pin with sufficient speed and force.